JP2787505B2 - Paper jam detector - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detection device for detecting paper jam when paper is moved from a feed port to a discharge port in a device such as a printer.

[Problems to be Solved by the Related Art and the Invention] Devices such as a printer and a copier are provided with a paper transport mechanism for feeding paper. In addition, these apparatuses are generally provided with a jam sensor for detecting when a paper jam (paper jam) occurs in the apparatus for some reason.

For example, a cut-sheet laser printer has two sensors provided along the paper conveyance path, and the paper does not pass through the rear sensor within a certain time after passing through the front sensor. In this case, it is detected that a jam has occurred.

However, for example, a printer that uses continuous paper cannot use the above detection method because there is no break in the paper.

[Purpose of the Invention] The present invention has been made in view of the above-mentioned problems, and also in an apparatus such as a printer using continuous paper,
An object is to provide a device capable of detecting paper jam.

Means for Solving the Problems In order to achieve the above object, a paper jam detection device according to the present invention includes a conveying unit that conveys a sheet along a conveying path, and a sheet that does not contact the sheet during normal conveyance. First detection means for contacting when the paper floats from the transport path and outputting different signals for non-contact and contact, and non-contact when the paper contacts the paper during normal transport and floats from the transport path; And a second detection unit that outputs different signals for non-contact and contact, and a paper contact signal is output from the first detection unit, or a paper non-contact signal is output from the second detection unit. And determination means for determining the occurrence of paper jam when the operation is performed.

[Example] Hereinafter, the present invention will be described with reference to the drawings. Fig. 1 ~
FIG. 3 shows an embodiment in which the jam detecting device according to the present invention is applied to a laser printer.

Here, a laser beam printer that prints print data from a host computer as a printer main body on continuous paper in accordance with an electrophotographic process of exposing a photosensitive drum to a photosensitive drum, developing an exposed image, transferring it to a paper surface, and fixing is shown. . Note that this printer is configured as a page printer that starts printing after print data corresponding to one page is accumulated, for convenience of printing by an electrophotographic process.

The continuous paper is a so-called fanfold paper, which is a foldable continuous paper with a feed hole, and is configured such that the folded portion becomes a perforation and can be easily cut. It should be noted that the printer is configured to perform printing avoiding perforations so that the printed data is not cut even when the paper is cut.

By the way, in a cut-sheet printer, it is sufficient to consider only printing on one sheet. Therefore, the interval between the transfer position and the fixing position is not a problem. Fixing wastes the paper for the interval described above, and therefore, there is a problem in which part of the transferred paper is fixed.

In consideration of printing performance, it is preferable that the transfer and fixing be interrupted and resumed at a perforation where printing is not continuous. Therefore, the interval between the transfer position and the fixing position is set to one page. It is preferable that a perforation, which is a page break, comes at the same time.

With this configuration, if printing is normally completed and the printer is in a standby state, one page of unfixed paper remains between the transfer position and the fixing position, and data for the next page is transferred. At this time, the page is fixed and discharged. As a result, it is possible to eliminate waste of paper caused by performing fixing for each transfer.

Note that the printer of this embodiment is based on the premise that continuous paper having a length of one page of 11 inches is mainly used, and therefore, the interval between the transfer position and the fixing position is set to 11 inches.

First, the mechanical configuration of the printer will be described with reference to FIGS.

This printer, as shown in FIG.
A process unit 10 having a photosensitive drum 11 as a center, and an endless projection having a projection engaged with a paper feed hole from a feed port 1 side to which the paper is supplied toward an output port 2 side from which a printed sheet is discharged. A tractor unit 20 having a belt 21 and a fixing unit 30 having a pair of rollers 31 and 32 for thermocompressing the transferred toner image are arranged in this order.

The process unit 10 includes a charger 12 for charging the photoconductor on the photoconductor drum 11, a scanning optical system 13 for exposing the charged photoconductor to form an electrostatic latent image on the drum, and A developing unit 14 for attaching toner to the latent image, a transfer charger 15 for charging paper to transfer this toner image to the continuous paper FP, a cleaning unit 16 for removing toner remaining on the drum, and a drum A charge removing LED 17 that removes electric charges by exposing the whole is provided.

The scanning optical system 13 is provided in the upper lid UC, and continuously deflects a modulated beam from a semiconductor laser (not shown) by a polygon scanner 13a, converges it by an fθ lens (not shown), and reflects the beam by a beam bender 13b. Thus, a scanning line is formed on the photosensitive drum 11, and an electrostatic latent image is formed in dot units as the drum rotates.

The developing unit 14 that supplies the toner includes a toner case 14a in which the toner is accumulated, and a developing roller 14 that is provided at a lower end of the case and attaches the toner to the photosensitive drum 11.
b, and a piezoelectric sensor as a toner low sensor 14c for detecting the presence or absence of toner in the case.

The transfer charger 15 is fixed to an arm 15a rotatable about a pivot L1 by a cam mechanism. A pair of guide rollers 18a and 18b located on both sides of the continuous paper FP are integrally fixed to the arm 15a.

At the start of printing, it is necessary to spin the drum without feeding the paper until the exposed portion of the photosensitive drum 11 reaches the transfer position. In this case, by lowering the arm 15a and lowering the guide rollers 18a and 18b, the paper is separated from the photoconductor drum 11, thereby shortening the life due to the wear of the photoconductor and preventing the paper from being stained by residual toner. be able to.

The toner removed from the photosensitive drum 11 by the cleaning unit 16 is put into a waste toner box 60 provided on the side of the photosensitive drum 11, as shown in FIG.

The fixing unit 30 includes a heat roller 31 having a halogen lamp for heating and a thermistor for detecting temperature inside, and a continuous paper FP inserted between the rollers.
And a pressing roller 32 for pressing the heat roller 31 against the heat roller 31 with a predetermined pressure.

The tractor unit 20 includes two endless belts 21 and 21 laid between a driven shaft 22 and a drive shaft 23 as shown in FIG.
Are driven from the main motor 40 via a feed clutch and a gear train provided in a box indicated by 41 in the figure.

Note that the drive shaft 23 of the tractor unit 20 is
In this drive gear train independent drive, the gear train is configured to transport the continuous paper FP at the tractor unit 20 at 50 mm / s, but if the paper is pulled at a faster speed than this, It has a built-in one-way clutch that idles with a predetermined resistance in accordance with the pulling speed.

The driven shaft 22 is connected to a disk 25 interlocking with the driven shaft 22 via a chain 24. The disk 25 has slits formed at predetermined intervals, and a pulse (hereinafter, referred to as a PFS pulse) corresponding to the moving amount of the paper is taken out from a photo interrupter 26 provided with the slit interposed therebetween. Can be. The PFS pulse is output once every 1/2 inch of the paper.

The heat roller 31 is rotatably driven from the main motor 40 via an F clutch and a gear train, and is configured to feed the continuous paper FP at 75 mm / s when nipped. Therefore, the actual driving of the continuous paper FP is performed by the fixing unit 30, and the above-described tractor unit 20 mainly performs a function of applying a back tension to prevent skew of the paper.

Next, a sensor for detecting a paper error will be described.

This printer has four types of sensors for detecting the presence or absence of paper along the paper transport path. The printer detects changes in paper transport speed, and the rise or swell of paper to detect paper breaks and jams. The occurrence has been detected.

The first is an empty sensor 50 that is provided between the feeding port 1 and the transfer position P1 and is pushed in when a sheet is set and turned off, and floats and turns on when the sheet runs out.
In this printer, when printing is stopped, a perforation, which is a break between pages, is transferred to the transfer position P1 where the photosensitive drum 11 is in contact.
The fixing position is set at the fixing position P2 which is in contact with the heat roller 31. Therefore, when the rear end of the last page of the sheet is located at the transfer position P1, the empty sensor 50 is turned on to detect the paper breakage.

Also, what inch of the paper is the transfer position P1, the fixing position P2,
In addition, whether it is located in the empty sensor part is PFS
Since the pulse can be detected by counting, if the sheet is cut at a portion other than the perforation, it can be detected from the output of the empty sensor of the count.

The second is provided between the anchoring unit 30 and the tractor unit 20,
Skew sensors 51, 51 which contact both ends of the continuous paper and detect skew or cut of the paper. This sensor is
Turns on when at least one of the papers rises,
Turns off when paper is normally fed.

The third sensor 52 is provided at the center of the skew sensor, and is turned on when the paper is set normally, and is turned off when the paper is not set or when the paper floats. This sensor functions as the second detecting means of the present invention by detecting the leading edge of the sheet at the start of printing and detecting the rising of the sheet due to a jam during printing.

The fourth is a jam sensor 53 provided on the upper lid UC at a position substantially opposed to the top sensor 52. This sensor functions as the first detecting means of the present invention by being turned on in contact with the sheet when the center of the sheet rises due to a jam in the fixing unit 30.

Next, error detection by the above-described sensors will be described with reference to FIG.

This flowchart is executed, for example, as an interrupt process for a print main sequence, and detects a paper-related error.

In this process, first, in step (in the figure, simply indicated as "S.") 1, the state of the empty sensor is determined. If the empty sensor is OFF, that is, if paper is set on the paper feed port 1 side,
In steps 2 and 3, it is determined from the state of the flag FTSET and the state of the top sensor whether or not the sheet setting has been completed. If the flag FTSET is 0 and the top sensor is OFF, it is determined that the paper setting has not been completed, and the paper setting processing of steps 4 to 9 is performed.

The paper setting process is a process that is executed when new continuous paper is set in the printer, and the paper is fed to the fixing position P2 by closing the top cover by aligning the top of the paper with the tractor unit 20. .

In steps 4 to 9, the paper is conveyed while monitoring the time-up of the timer and the change of the top sensor to ON.
Carry the paper until it is counted 7 times and set the flag FTSET to 1
And terminates the error detection normally.

When the PFS pulse is counted five times after the leading edge passes through the top sensor, the leading edge of the sheet reaches the fixing position P2, and the next perforation is located at the transfer position P1.
However, even if the leading end of the sheet has reached the fixing position P2, the sheet may not be nipped when the pressing roller is raised. Therefore, when the paper is set, the paper is further fed by one page (22 pulses), and the boundary between the first page and the second page is set to the fixing position P2. Therefore, the first two pages are ejected as blank pages, and the first page to be printed is the third page.

If it is determined in step 3 that the top sensor is ON, steps 4 to 8 are skipped, a flag is set in step 9, and the process ends normally. Since the flag FTSET is reset to 0 upon initialization when the power is turned on, the flag FTSET may be set to 0 even when paper is set.
In such a case, in order to prevent the paper from being wasted by performing the idle feeding of the paper, the determination in step 3 is performed.

If the timer expires before the top sensor turns on, it is determined that a jam has occurred and the step
In step 10, the flag FTSET is set to 0, and in step 11, a message indicating that a jam has occurred is displayed on the operation panel, and error processing is started. The error process is a process of turning off the power of a motor, a heater, and the like to stop the operation of the printer.

If it is determined in step 2 that the flag FTSET is 1, the states of the top sensor, the jam sensor, and the skew sensor are sequentially determined in steps 12, 13, and 14, and if the paper is floating, If an abnormality is detected from at least one of the sensors, error processing is started via steps 10 and 11. If the flag FTSET is 1, it indicates that the paper setting has been completed. Therefore, in a normal state, the top sensor is ON, the jam sensor is OFF, and the skew sensor is OFF.

Next, if it is determined in step 1 that the empty sensor is ON, that is, if there is no more paper in the feed port 1 due to paper exhaustion or the like, the state of the top sensor is determined in step 15 and this is turned ON. The transfer, that is, if untransferred and unfixed paper remains in the printer,
In step 16, the sheet is fixed and discharged. If the top sensor is OFF, step 16 is skipped, and in steps 17 and 18, the flag FTSET is set to 0 to indicate that the paper is out, and the error processing starts.

As described above, by using the function of the top sensor according to the situation according to the situation, detection of a paper setting request, detection of a paper jam, and necessity of form feed when paper is exhausted, a situation suitable for a printer for a continuous paper is provided. Can be grasped.

[Effects] As described above, according to the present invention, paper jam can be detected even in a device such as a printer using continuous paper.

Further, by providing the detecting means at two places and judging by combining these outputs, the jam detection can be performed more accurately.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a printer provided with a paper jam detecting device according to the present invention, FIG. 2 is a plan view of a paper transport portion of the printer shown in FIG. 1, and FIG. 3 is a flowchart of jam detection. DESCRIPTION OF SYMBOLS 1 ... Feeding port 2 ... Discharge port 10 ... Process part 20 ... Tractor part (transportation means) 30 ... Fixing part 52 ... Top sensor (second detection means) 53 ... Jam sensor (first Detection means)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masahiro Kita 2-36-9 Maenocho, Itabashi-ku, Tokyo Inside Asahi Optical Industry Co., Ltd. (72) Inventor Takaaki Yano 2-36-9 Maenocho, Itabashi-ku, Tokyo No. Asahi Optical Co., Ltd. (72) Inventor Ryoji Honda 2-36-9 Maenocho, Itabashi-ku, Tokyo Asahi Optical Co., Ltd. (72) Inventor Tsutomu Sato 2-36-9, Maenocho, Itabashi-ku, Tokyo No. Asahi Optical Industry Co., Ltd. (72) Inventor Shoji Kamasako 2-36-9 Maenocho, Itabashi-ku, Tokyo Asahi Optical Industry Co., Ltd. (56) References JP-A-63-288855 (JP, A) Kaisho 59-192065 (JP, U)

Claims (1)

(57) [Claims] 1. A conveyance means for conveying a sheet along a conveyance path, wherein the signal does not come into contact with the sheet during normal conveyance but comes into contact when the sheet rises from the conveyance path, and a different signal is output between non-contact and contact. First detection means for outputting, and second detection means for contacting the sheet during normal conveyance, making non-contact when the sheet floats up from the conveyance path, and outputting different signals for non-contact and contact, A determination unit configured to determine occurrence of paper jam when a paper contact signal is output from the first detection unit or a paper non-contact signal is output from the second detection unit. Paper jam detector.